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How do they make mulch?

Discussion in 'Landscape Architecture and Design' started by tjcezar, Nov 26, 2006.

  1. tjcezar

    tjcezar LawnSite Member
    from PA
    Posts: 237

    Can someone tell me the process to making mulch (like a double ground hardwood or other). I know they take brush piles and such and grind them in a tub grinder but what gives the dark color etc. What would the process be from start to finish
  2. Uranus

    Uranus LawnSite Bronze Member
    from Mass
    Posts: 1,624

    Other- toss 1000 used tires into a grinder and dye red = red rubber mulch
  3. AGLA

    AGLA LawnSite Bronze Member
    Posts: 1,742

    Bark mulch is the by product of lumber mills where they debark logs prior to turning them into lumber.

    Take a look at the "take a tour of our sawmill" on this web site. About the tenth slide in...
  4. paponte

    paponte LawnSite Silver Member
    Posts: 2,366

    Brown mulch gets it's color naturally during decomposition. Piles are turned often just like leave piles and decompose from bacteria, heat, nitrogen, ammonia, etc. Next time your near a pile stick a thermometer in one, you'll be surprised the heat they produce. :)
  5. tjcezar

    tjcezar LawnSite Member
    from PA
    Posts: 237

    Would you say that the brush, stumps, and other woody material are collected and then fed through a tub grinder and then possibly through again for say double ground mulch? I saw an operation spraying the mulch with something as it came out of the grinder and was wondering if that was just water to help with decomposition or something else.
  6. paponte

    paponte LawnSite Silver Member
    Posts: 2,366

    could have very well been water. Have to keep the stuff moist for it to decompose properly. Some mulches are dyed and treated for insects and such. Yes it is shredded, then usually double or even triple hammered after that. Many places line up their material and run over them with machines called scarabs. Pretty much machines with flails that turn the piles.
  7. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,192

    Making mulch might be a good business, they charge us to drop off the brush for them to grind. It is alot cheaper to take brush to these grinder guys then to a land fill.....pickup is $5 if not stacked very high. We believe we are getting a lot of nut grass coming in the mulch, not good.
  8. mdvaden

    mdvaden LawnSite Bronze Member
    Posts: 1,944

    Some places even sell "Certified" compost now.

    I think that's the kind which also is ensured to have reached 160 degrees or so for temperature.

    MOW PRO LAWN SERVICE LawnSite Bronze Member
    Posts: 1,566

    Local factories here have a pallet grinder which is turned into mulch.
  10. Mr. Vern

    Mr. Vern LawnSite Senior Member
    Posts: 632

    We produce mulch in our facility. There are several methods used, we use a tub grinder. Tub grinders and horizontal grinders have a hammer mill that "hogs" the wood; which is basically a set of swinging hammers that beat the wood against anvils or cutting edges and pulverise the wood. THe chunks of wood will pass by a set of screens that will determine the size of product that gets through and therefore the size of the mulch. The next step we use is to run the mulch through our screening plant which produces 3 products; fines, mulch and overs. The fines we mix with our soil blends, the mulch we either run through our coloring plant or sell as walk-on bark/Decco chips, and the overs get put back through the grinder. THere are other methods such as schredding which typically gives the longer shredded looking products that you might see. THe water you see being sprayed is probably either for dust suppresion or in some cases fire suppression.
    It is true that you can make good money in mulch, but it's not easy money. We have a $600k tub grinder, a $250k excavator to load it with, a $300k screening plant and a $100k coloring machine. The grinder alone has a 990 hp Cat Diesel that drinks just over 50 gallons of diesel/hr(yes that is per hour). So when you pay $5 to drop off your limbs and then come back and pay $37 for the yard of colored mulch it became, don't just assume that someone just made $42 profit off of you.
    As for the certified compost - it is most likely "certified Organic". The certification is to validate that no chemicals were used to accelerate the composting process, or to color the product to make it appear more composted. It should come with certs (if you request them) that show precisely what the Carbon to Nitrogen ratios are, as well as other key data.

    As for the Nutgrass seed, anything is possible, but in our yard we do not accept yard clippings, but only wood waste. THis reduces the chances of introducing weeds(not the main reason we don't accept. It is because the nitrogen content heats the piles too quickly), but by no means eliminates it. Piles also heat up very fast so any weed seed has a good chance of being killed as well. Still, the possibility certainly exists that you could introduce weed seeds by applying mulch.

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